The instant invention relates to electrophotographic apparatus, and more particularly to electrophotographic apparatus in which a photoconductor, movable past a plurality of electrophotographic stations, has an insulating support web with, in turn, an electrically conductive layer, and a photoconductive layer disposed thereon, in which there is or can be an electrical connection between the electrically conductive layer and a stationary contact at a fixed potential.
In the field of electrophotographic reproduction today, increasing use is being made of photoconductors that consist not of a rigid metal roller having a photoconductive material disposed thereon but of a flexible web comprising a support, a conductive layer and a photoconductive layer. If such photoconductors are not disposed on drums, but are used in the form of continuous webs which are conveyed, for example, by several guide rollers, there is some difficulty in bringing the electrically conductive metal layer of this photoconductor into electrical contact with a fixed potential elsewhere on the apparatus. This electrical contact must be effective and reliable, and at the same time must not destroy the very thin metal of the conductive layer during the working life of the photoconductor.
Numerous attempts already have been made to achieve an effective and reliable contact which does not destroy the conductive layer of the photoconductor, including an attempt to produce the contact by rolling as opposed to sliding. In this case, too, however, the electrically conductive layer was destroyed long before the photoconductor was worn out. The use of metallic conductive brushes has also resulted in a very rapid destruction of the electrically conductive layer of the photoconductor.
A recent approach to the electrical contact problem in photoconductor webs is described in U.S. Pat. No. 4,027,967, issued June 7, 1977, wherein the contact is achieved using a stationary graphite surface. However, graphite is extremely brittle, and if the graphite breaks, an electrical short may develop possibly causing a fire to occur.
The instant invention accordingly provides an electrical grounding device for the photoconductor having all the advantages of graphite but without the brittleness of graphite and the attendant fire hazard.